Acute effects of hydrocortisone on the reabsorption of inorganic phosphate in normal, adrenalectomized and parathyroidectomized rats.

Clearance studies have been performed in order to examine the acute effects of hydrocortisone on the reabsorption of inorganic phosphage (Pi) in normal, acutely adrenalectomized (Adr. X) and acutely parathyroidectomized (PTX) rats. Hydrocortisone increased the glomerular filtration rates in all groups, normalized the capacity to excrete water in the Adr. X animals, did not change consistently the fractional reabsorption of sodium in all series and diminished the fraction reabsorption of inorganic phosphate in Adr. X rats from 91.4 +/- 6.5 (mean +/- S.D.) to 78.2 +/- 8.5% (P less than 0.001). It is concluded that the decrease of the fractional reabsorption of Pi in the Adr. X animals was rather the result of the increased filtered load than a direct effect of hydrocortisone on the Pi transport.